Advanced data processing and communication systems are comprised of numerous components or subsystems. Types of advanced data processing systems typically include a super computer utilizing an array of processors, a super-memory utilizing an array of data storage devices, a neural network or a combination of devices, any one of which operates at very high data or processing rates. Advanced communication systems typically include communication hubs for local area networks and other types of networks. The emphasis in the design and development of these advanced systems has primarily been on increasing the operating rates of discrete system components and interconnecting larger numbers of components to achieve greater processing or networking capabilities. With increases in the operating rates of the discrete system components and the number of interconnections comes an increasing demand on the system's signal distribution network for ultra-high speed transfers of large amounts of data between the components of the system.
Current signal distribution systems in advanced processing systems rely on backplanes and other types of communication busses using wires and cables that require very large numbers of connections between components. Because of the number of connections required, and because of the limited bandwidth or data rates of conventional cabling, optimal system architectures are rarely achieved. Consequently, data transfers between components are accomplished at data or signalling rates magnitudes slower than the operating rates of at least the faster system components, and access times for the system are significantly longer. In sum, the overall performance of an advanced processing system is limited by the conventional signal distribution systems.
To achieve optimal system architectures or configurations of the components in an advanced data processing system, several problems must be overcome. For example, there are physical limitations in the number of input/output (I/O) pins available for interconnecting the components, not only limiting the number of components that can be interconnected, but also limiting the available bandwidth. The number of signal interconnections is also limited by loading effects where the signal is "fanned-out" from the transmitter of one component to the receiver of several components. The transmitter has limited output power.
Increasing the bandwidth by increasing the data or signalling rates exacerbates several other problems. Voltage standing waves on cabling cause multipath "echoes", especially in a "fan-in" distribution system where a receiver is coupled to more than one transmitter. Cross-talk induced by magnetic coupling of proximate cabling increases with the signalling bandwidth. Thus, the task of data detection at the receivers become much more difficult, especially when interference is taken into account, as data rates increase. Voltage standing waves in the signal distribution system causes signal reflection problems, slow access times to logic devices, and limited bandwidth. Each of these problems are exacerbated by increasingly faster signalling and data rates. To compensate for some of these problems, additional data buffers, rate-smoothing interfaces, memories and processors are incorporated into the distribution system, thus increasing the processing system's design complexity and cost.
At higher data speeds, the physical layout of the components of the advanced data processing system become critical. The number of connections, for example, between the processing and control equipment, disk and tape units and external I/O devices, requires large amounts of cable. Beside the logistical problems of dealing with so much cabling, high speed data does not travel well on long cables due to narrow bandwidth, significant power loss and relatively slow travel speeds. In present advanced data processing systems, components that require fast access to "remote" data are positioned in close proximity to the data source. Furthermore, there are time skew problems where several components require access to the same data at the same time. One solution to these problems has been to resort to densely-packed, super-cooled modules that are "bricked" into a computing structure. However, "bricking" leaves very little space for architectural modifications and requires unacceptable downtime for repairs.
In the end, advanced processing and communication systems requiring large bandwidths and large numbers of interconnections force high-risk, high-cost and high-density solutions that are more difficult to design than the algorithms being processed, and are difficult to maintain in the field. What is required is an ultra-wideband signal distribution system for large-scale advanced data processing and communication systems.